Author Topic: 74 Eldorado EGR question  (Read 73 times)

Offline danjarrett1

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  • Name: D Jarrett
74 Eldorado EGR question
« on: January 07, 2018, 11:31:54 PM »
Has anyone had any experience with servicing or replacing th EGR valve? I know they can carbon up and cause problems. I understand that  some of them can be cleaned up with solvent or otherwise. Or, has anyone just removed it altogether, plugged off the vacuum lines and sealed it over with a steel plate and gasket?
1974 Cadillac Eldorado convertible
2007 Cadillac Escalade
1980 Cadillac Seville “Bustleback”

Offline TJ Hopland

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Re: 74 Eldorado EGR question
« Reply #1 on: January 08, 2018, 08:08:34 AM »
You should still be able to buy a replacement but it won't look identical to the original.  They way the replacements work is they come with an assortment of orifice washers.  The instructions have a list of OE part numbers so you look up the original number and it tells you which washer to install. 

As for removing it a small block chev fuel pump block off plate is easy to find and easily modified to fit.   If its an otherwise stock engine I think I would just replace it.   If you remove them you tend to start having lean issues and detonation since the factory 'tune' expected to have it there and working. 

What issues are you having?   EGR leaking will usually cause rough idle.  Not working detonation issues especially at cruise.   
StPaul/Mpls, MN USA

73 Eldo convert w/FiTech EFI
75 Eldo rusty but trusty
80 Eldo Diesel
And other assorted stuff I keep buying for some reason

Online 35-709

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  • Name: G. Newcombe
Re: 74 Eldorado EGR question
« Reply #2 on: January 08, 2018, 08:57:15 AM »
Here is a good video about EGRs, how they work, how to test (easy), and how to clean.  It involves a Corvette but the valves are basically the same. 
1935 Cadillac Sedan resto-mod "Big Red"
1973 Cadillac Caribou - Sold
1950 Jaguar Mark V Saloon resto-mod

Offline "Cadillac Kid" Greg Surfas 15364

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Re: 74 Eldorado EGR question
« Reply #3 on: January 08, 2018, 09:26:57 AM »
Maybee I have been lucky but I have never had an EGR that didn't function.  What frequently happens is that soot and carbon builds up between the seat and the valve "disc" causing the valve to continuously leak.  What I have done is to unbolt the valve, get it to a place where I can see the operation and then apply vacuum to the nipple. If the valve moves you should be able to clean it up by scraping away the big chunks and then using carb spray on the inside of the valve (not the vacuum actuator. 
When replacing the valve with a new gasket you can deactivate the system by not connecting the vacuum line.  The valve is a normally closed valve and if it is clean enough it will not leak.
I've got a couple of valves here and I'll post a picture later this PM.
I don't remember if you answered this question in one of your earlier posts, but a factory service manual and a Fischer body manual for 1974 will be worth their weight in gold, especially when you get to an electrical or AC issue.
Greg Surfas
« Last Edit: January 08, 2018, 09:28:57 AM by "Cadillac Kid" Greg Surfas 15364 »
Cadillac Kid-Greg Surfas
CLC #15364
66 Coupe deVille (now gone to the UK)
72 Eldo Cpe  (now cruising the sands in Quatar)
73 Coupe deVille
75 Coupe deElegance
76 Coupe deVille
79 Coupe de ville with "Paris" (pick up) option and 472 motor
514 inch motor now in '73-


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